Physiological recording device or electrode

ABSTRACT

The present invention is directed to a physiological recording device, or other types of sensors to detect a biopotential, and more particularly, a physiological recording electrode that can be used without skin preparation or the use of electrolytic gels. The invention is further directed to the configurations of structures on the physiological recording electrode&#39;s lower surface. The structures having a length, width, and height, which are capable, at least in part, of transmitting an electric potential from the skin which can be measured. The structures may or may not limit the depth of application, and/or anchor the electrode or other device during normal application, and/or allow for uniform application of the electrode or other device over unprepared skin.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patentapplication Ser. Nos. 10/988,358 filed Nov. 12, 2004; 11/401,559 filedApr. 11, 2006, U.S. Pat. No. 7,286,864 which is a continuation of Ser.No. 10/874,075 filed Jun. 22, 2004 issuing into U.S. Pat. No. 7,032,301,which was a continuation of Ser. No. 09/949,044 filed Sep. 7, 2001issuing into U.S. Pat. No. 6,785,569; and Ser. No. 11/454,520 filed Jun.16, 2006 whose specifications are herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a physiological recording device,or other types of sensors to detect a biopotential, and moreparticularly, a physiological recording electrode that can be usedwithout skin preparation or the use of electrolytic gels. The inventionis further directed to a variety of configurations of structures on thephysiological recording electrode's lower surface.

2. Technical Background

Electrodes for measuring biopotential are used extensively in modernclinical and biomedical applications. These applications encompassnumerous physiological tests including electrocardiography (ECG),electroencephalography (EEG), electrical impedance tomography (EIT),electromyography (EMG) and electro-oculography (EOG). The electrodes forthese types of physiological tests function as a transducer bytransforming the electric potentials or biopotentials within the bodyinto an electric voltage that can be measured by conventionalmeasurement and recording devices.

In general, most commercial physiological electrodes for theseapplications today are placed on the surface of the skin. Because ofthis it is important to understand the anatomy of the skin to understandthe problems encountered with these electrodes. The skin is a layeredstructure, which consists of the epidermis and the dermis. The dermiscontains the vascular and nervous components. Further it is the part ofthe skin where pain has its origins. The epidermis is an important layerin the electrode/skin interface. The epidermis consists of a number oflayers as shown schematically in FIG. 1. These layers consist of:

a) Stratum basale or stratum germinativum, which contains living basalcells that grow and divide, eventually migrating into the other layersof the epidermis;

b) Stratum spinosum, which contains living cells that have migrated fromthe stratum basale. The early stages of desmosomes can be found in thislayer;

c) Stratum granulosum, which contains cells with many desmosomalconnections, forms a waterproof barrier that prevents fluid loss fromthe body;

d) Stratum lucidum, which is a transition layer between the stratumgranulosum and the stratum corneum. It is thickest in high frictionareas such as the palms and the soles of the feet; and

e) Stratum corneum, which is the outer layer, contains dry, dead cells,flattened to form a relatively continuous thin outer membrane ofrelatively continuous thin outer membrane of skin. The deeper cells ofthis layer still retain the desmosomal connections, but as they arepushed toward the surface by newly formed cells in the underlyinglayers, the junctions gradually break and the cells are lost.

The stratum corneum is the primary source of high electrical impedance.This is because dead tissue has different electrical characteristicsfrom live tissue, and has much higher electrical impedance. Thus, thislayer dramatically influences the biopotential measurements. The stratumcorneum is estimated to be typically approximately one tenth thethickness of the epidermis except for the palms of the hand and the footwhere this layer is much thicker. The stratum corneum, further, is verythin and uniform in most regions of the body surface ranging from 13-15μm with a maximum of about 20 μm. If the high impedance results from thestratum corneum can be reduced, a more stable electrode will result.Therefore with existing physiological electrodes the skin must beprepared prior to application when lower impedance is required.

The most common electrode preparation methods to improve the electrodesignal and avoid the high impedance effects of the stratum corneumare: 1) shaving the hair from the skin; and 2a) abrading the stratumcorneum and/or 2b) using an electrolytic gel. Electrodes having or usingan electrolytic gel or fluid are often referred to as—“wet” electrodes.Hair is shaved from the skin to improve the contact between theelectrodes and the skin surface. The goal of the abrasion of the stratumcorneum is to reduce the thickness of (or remove) the stratum corneum(and therefore its electrically insulating characteristics). Drawbacksof abrading the skin are that the abraded area regenerates dead cellsfairly quickly (resulting in a limited time period for using theelectrode), and if the abrasion is too deep the person can experiencepain. Additionally, electrolytic gels or fluids may be applied toabraded surface to enhance the contact. Alternatively, electrolytic gelsor fluids can be applied to the surface of the skin directly. Theelectrolytic gel, having a high concentration of conductive ions,diffuses into the stratum corneum and improves its conductivity.Drawbacks observed with the use of electrolytic gels or fluids involvethe change of conductivity with time as the gels dry, discomfort (anitching sensation) at the patient's skin as a result of the gels drying,and the possibility of a rash due to an allergic reaction to theelectrolytic gels.

Further drawbacks of “wet” electrodes include skin preparation andstabilization of the electrode with respect to the skin surface. This isbecause movement of the electrode on the surface of the skin causes thethickness of the electrolytic layer (formed by the electrolytic gels orfluids) to change resulting in false variation in the measuredbiopotential commonly referred to as motion artifacts. Some electrodedesigns have an adhesive backing to reduce the movement of the electrodeon the skin surface. However, neither of these features eliminatescompletely the movement of the electrode with respect to the subject'sskin. Another drawback is the length of time required to prepare theskin and apply the electrolytic gels or fluids prior to measurement ofthe biopotentials.

A less common type of physiological electrode is a non-polarizable “dry”electrode. These ceramic, high sodium ion conducting electrodes do notneed an electrolytic gel before their application. The principal of themeasurements from these physiological electrodes is based on a sodiumion exchange between the skin and the electrode. The skin-electrodeimpedance of these type of electrodes are found to decrease as afunction of application time. This is a result of perspiration beingproduced by the body under the electrode almost immediately afterapplication of the electrode on the skin. Drawbacks again, however,include many of those experienced with “wet” electrodes.

Another less common type of physiological electrode is an active “dry”electrode with an amplifier. Advances in solid-state electronictechnology have made it possible to record surface biopotentialsutilizing electrodes that can be applied directly to the skin withoutabrading the skin or using an electrolytic gel. These electrodes are notbased on an electrochemical electrode-electrolyte interface. Rather,these electrodes are active and contain a very high impedance-convertingamplifier. By incorporating the high impedance-converting amplifier intothe electrode, biopotentials can be detected with minimal or nodistortion. Although these electrodes offer the advantage of notrequiring some of the preparation needed with conventional electrodes,they have certain inherent disadvantages. These electrodes are bulky insize due to the additional electronics and power sources required andthey are typically more expensive to produce due to the electronicassembly required. Further, these electrodes also result in motionartifacts due to poor electrode-skin contact similar to electrodesrequiring electrolytic gels or fluids.

In view of the foregoing inherent disadvantages with presently availablewet and dry electrodes, it has become desirable to develop an electrodethat does not require skin preparation or the use of electrolytic gelsand overcomes the inherent disadvantages of presently available dryelectrodes.

SUMMARY OF THE INVENTION

The present invention is directed to a physiological recording device,and more particularly, a physiological recording electrode that can beused without skin preparation or the use of electrolytic gels. Theinvention is further directed to the shape of the physiologicalelectrode's lower surface, as well as a variety of configurations ofsurface structures on the physiological recording electrode's lowersurface. These surface structures have various lengths, widths, andheights, which are preferably rigid and resist breaking, and arecapable, at least in part, of transmitting an electric potential fromthe epidermis of the skin which can be measured. The surface structuresmay be used: to limit the depth of application, to anchor the device, orpreferably the electrode during normal application, to penetrate theskin surface, to increase skin/electrode surface contact, and/or toallow for uniform application of the electrode or other device overunprepared skin.

The physiological recording device, has an upper and a lower surface.The lower surface can take many forms. For instance, the lower surfacecan be flat, concave, convex, or some other unique shape. Thephysiological recording device can be substantially flat on its lowersurface. Various embodiments of the present invention could includechanges in the physiological recording device's lower surface. Whetherthe lower surface is perpendicular to the device's vertical axis, orsloped depends on the application. The physiological recording devicecan also be substantially concave on its lower surface. An example iswhere the lower surface is outwardly curved like a portion of the innersurface of a large sphere. The physiological recording device can alsohave a convex shape on its lower surface. An example is where the lowersurface curves or bulges outward, like a portion of the exterior surfaceof a large sphere. The lower surface of the physiological recordingdevice is not limited to one of the aforementioned shapes, and may takeon a number of other unique shapes or some combination of the shapeslisted above.

The lower surface of physiological recording device of the presentinvention may further include a number of surface features. Thesesurface features may take one of many forms including but not limited toridges, columns, penetrators, anchors, epidermal stops and combinationsthereof. These surface features, in general, protrude from the variousshaped substrates described above. Preferably, there is at least onestructure or surface feature protruding from the electrode's lowersurface. One of the important functions of the configuration of surfacefeatures is to displace or move the hair, dead skin cells and/ordetritus so that the surface features can better collect the electricalbiopotentials generated by the body.

The ridge(s) as used in the present invention is preferably a long,narrow structure or elevation. The ridge(s) can have a variety of crosssections over a length. Examples of these cross sections include but arenot limited to a square, rectangle or trapezoid, a pointed surface likethat of a triangle, a domed surface like that of an arch or arc, a crosssection with a concave surface between to ridge lines forming the tworidge lines, some other unique cross-section or the like. The crosssection of the ridge extends for a length. The length of the ridge ispreferably substantially longer than the height or width of thecross-section of the ridge. The surface of the ridge away from thesubstrate, when applied to the skin surface, depresses, but does notneed to pierce the skin but anchors the electrode in place to preventmotion artifacts, to diplace hair, dead skin cells and/or detritus, toincrease the surface area of the electrode in contact with the skin, andto be capable, in part, of transmitting an electric potential which canbe measured from the surface of the skin through the ridge.

A column(s) is another type of structure or elevation that can be usedin the present invention. A column(s) can have a variety of crosssections over a length. Examples of these cross sections include but arenot limited to a square, rectangle or trapezoid, a pointed surface likethat of a triangle, a domed surface like that of an arch or arc, a crosssection with a concave surface between two points (wherein the distancefrom the base to either point is greatest height of the column for thecross-section), some other unique cross-section or the like. The crosssection of the column like a ridge extends for a length. However, thewidth of the column is preferably in proportion to the height of thecross-section of the column, and more preferably shorter than the heightof the column. The surface of the column away from the substrate, whenapplied to the skin surface, depresses, and does not easily pierce theskin but anchors the electrode in place to prevent motion artifacts, todisplace hair, dead skin cells and/or detritus, to increase the surfacearea of the electrode in contact with the skin, and to be capable, inpart, of transmitting an electric potential which can be measured fromthe skin through the ridge.

A penetrator(s) is also a surface feature that can be used in thepresent invention. The penetrator(s) is sized and shaped for piercingthe stratum corneum or outer layer of the epidermis, and accessing thelower layers of the epidermis. The penetrator can take many shapesincluding but not limited to pyramidal, needle-like, triangular, or anyother shape that can be tapered to a point or tip. The surface of thepenetrator away from the substrate, when applied to the skin surface,readily pierces the skin, preferably anchors the electrode in place toprevent motion artifacts or any substantial movement, increases thesurface area of the electrode in contact with the skin and lower layersof the epidermis, and is capable, in part, of transmitting an electricpotential which can be measured from the skin and lower layers of theepidermis through the penetrator.

The epidermal stop(s), which can be used in the present invention is astructure or elevation. Epidermal stops are structures of a particularheight with respect to the height of the penetrator(s) or other surfacefeatures so as to prevent the penetrator(s) or other surface featuressuch as columns and ridges from penetrating into the dermis of the skinor unduly distorting the surface of the skin, respectively, where theymight cause discomfort to the subject. An epidermal stop(s) may also beincorporated into a penetrator, ridge, column or like surface feature orcan be a separate surface feature. The epidermal stops may, however,have any shape known to those skilled in the art that would effectivelyprevent the penetrator(s) from entering the dermis of the skin, or frombeing applied to deeply. The epidermal stops are preferably applied inan array among the penetrators, therefore further minimizing inadvertentdeep penetration or over penetration by the penetrator(s) or minimizingsignificant distortion of the skin by other surface structures. If theepidermal stop is a separate surface feature or incorporated intoanother structure, preferably, the epidermal stop in combination with atleast one other surface feature or two structures with incorporatedepidermal stops create a detritus trough.

A detritus trough is the area interposed between adjacent surfacestructures or features. These troughs, when provided or naturallyoccurring in the design, allow for a more accurate placement of thesurface features by allowing for displacement of the hair and otherdetritus on the skin in these troughs. Preferably, the detritus troughsare sufficient in number and size to allow for placement of the deviceon skin with a significant amount of hair such as for example the scalpor the chest of a male subject. Detritus troughs are created to maximizethe area available for optimal device to skin contact, by improving theprobability that hair and other detritus will enter the troughs and notpreventing the surface features from either coming in contact with theskin or penetrating the skin. Thus detritus troughs may be parallel toone another, perpendicular to one another, or in any other orientationmade to improve the contact of the device with the skin of the subject.

An anchor(s), which can be used in the present invention is a structureor elevation that stabilizes the physiological device against asubject's skin. This stabilization further preferably prevents motionartifacts in the electrophysiological signal from the device, or anysubstantial movement. While the anchor can also be any of the structuresdescribed above, the anchor may also serve no other purpose except tostabilize or reduce movement of the device on the subject's skin. Theanchor(s) can have a variety of cross sections over a length asdescribed above for the various surface structures.

It is understood that the physiological recording devices of the presentinvention may have a combination of the various surface featuresdescribed above. Various specific embodiments for the present inventionare described as follows: In one embodiment, the present inventionincludes a physiological recording device comprising a substrate havingan upper and a lower surface, and at least one ridge(s) formed on thelower surface, having a length, width, and height, wherein the ridge(s)depresses or pierces the stratum corneum or outer later of the skin, andis capable of transmitting an electric potential that can be measuredfrom the skin through the ridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, at least one ridge(s) formed on the lower surface, and at leastone penetrator wherein the penetrator is capable of depressing orpiercing through the stratum corneum or outer layer of the skin, theridge(s) pierces or depresses the stratum corneum or outer later of theskin, and both the penetrator and ridge in combination are capable, atleast in part, of transmitting an electric potential that can bemeasured from the skin.

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms an arc whereinthe ridge(s) depresses and/or pierces the stratum corneum or outer layerof the skin and is capable, at least in part, of transmitting anelectric potential that can be measured from the skin through theridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms a trapezoidwherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and is capable, at least in part, oftransmitting an electric potential that can be measured from the skinthrough the ridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms a trianglewherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and is capable, at least in part, oftransmitting an electric potential that can be measured from the skinthrough the ridge(s).

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, and at least one ridge formed on the lower surface,the cross section of the at least one ridge at least in part formscup-like, parabolic end comprising two outer points and an inner bowlwherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and is capable, at least in part, oftransmitting an electric potential that can be measured from the skinthrough the ridge(s).

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially convex and at least one structure being formed on thelower surface, wherein the structure is capable, at least in part, oftransmitting an electric potential that can be measured from the skin.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially concave and at least one structure being formed on thelower surface, wherein the structure is capable, at least in part, oftransmitting an electric potential that can be measured from the skin.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially curved and at least two structures being formed on thelower surface, the at least two structures both having different heightsand/or shapes, wherein the at least two structures are capable, at leastin part, of transmitting an electric potential that can be measured fromthe skin.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate not beingsubstantially convex, concave, or flat, but rather is neither uniformnor substantially symmetric, and at least two structures being formed onthe lower surface, the at least two structures both having differentheights and/or shapes, wherein the at least two structures are capable,at least in part, of transmitting an electric potential that can bemeasured from the skin.

In still another embodiment, the present invention includes aphysiological recording device for measuring physiological signals fromthe skin of subject comprising a substrate having an upper and a lowersurface, and at least one structure being formed on the lower surface,wherein the at least one structure does not readily pierce the skin ofthe subject, assists in anchoring the physiological recording device tothe skin of the subject and is capable, at least in part, oftransmitting an electric potential from the skin that can be measured.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, and at least one ridge formed on the lower surface,the cross section of the at least two ridges formed on the lowersurface, the at least two ridges being configured to create a detritustrough to allow for displacement of hair, dead skin cells and/ordetritus on a skin of a subject, wherein the at least two ridges arecapable, at least in part, of transmitting an electric potential thatcan be measured from the skin through the ridge(s).

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention, and together with the description serve to explain theprinciples and operation of the invention.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1. Cross-sectional view of the epidermis layer of a person's skin.

FIG. 2. Cross-sectional view of the epidermis layer and an illustrationof the insertion of the penetrator(s) into the epidermis layer.

FIG. 3. Isometric view of a physiological recording electrode

FIG. 4. Isometric view of a physiological recording electrode withpenetrators on its lower surface.

FIG. 5. Side view of a physiological recording electrode with a convexlower surface populated with penetrators that are the same height.

FIG. 6. Side view of a physiological recording electrode with a convexlower surface populated with penetrators that are varying in height inproportion to the curvature of the surface.

FIG. 7. Side view of a physiological recording electrode with a concavelower surface populated with penetrators that are the same height.

FIG. 8. Side view of a physiological recording electrode with a concavelower surface populated with penetrators that are varying in height inproportion to the curvature of the surface.

FIG. 9. Side view of a physiological recording electrode with a convexlower surface populated with penetrators and ridges that are the sameheight and epidermal stops that are shorter in height than thepenetrators.

FIG. 10. Side view of a physiological recording electrode with a convexlower surface populated with ridges that are the same height, andextending out like tentacles.

FIG. 11. Side view of a physiological recording electrode with a flatlower surface populated with penetrators that are varying in height.

FIG. 12. Isometric view of a physiological recording electrode withpenetrators on its flat lower surface arranged in a spiral.

FIG. 13. Isometric view of a physiological recording electrode withtrapezoidal ridges on its flat lower surface arranged in concentricrings.

FIG. 14 a) Isometric view of a physiological recording electrode withtrapezoidal ridges on its flat lower surface arranged in straightparallel lines; b) Isometric view of a physiological recording electrodewith trapezoidal ridges on its flat lower surface arranged inperpendicular groupings.

FIG. 15. Isometric view of a physiological recording electrode withtriangular ridges on its flat lower surface arranged in non-continuousconcentric rings.

FIG. 16. Isometric view of a physiological recording electrode with fourvarying topographic regions have penetrators in one region, ridges inanother region, thatch-like penetrators in another region, and acombination of ridges and penetrators in another region on its flatlower surface.

FIG. 17. Isometric view of a physiological recording electrode withpenetrators on its flat lower surface arranged in a thatch-like pattern.

FIG. 18. Isometric view of a physiological recording electrode withinterlocked columns on its flat lower surface.

FIG. 19. Isometric view of a physiological recording electrode withcup-ended columns on its flat lower surface arranged in parallel lines.

FIG. 20. Isometric view of a physiological recording electrode withtrapezoidal columns on its flat lower surface arranged in clusters withchannels.

FIG. 21. Isometric view of a physiological recording electrode withtriangular ridges on its flat lower surface arranged in a seven smallrings.

FIG. 22. Isometric view of a physiological recording electrode withtriangular ridges on its flat lower surface arranged in non-concentricrings.

FIG. 23. Isometric view of a physiological recording electrode withpyramidal columns on its flat lower surface.

FIG. 24. Isometric view of a physiological recording electrode withpenetrators on its flat lower surface arranged in clusters withchannels.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is related to a physiological recording device,and more particularly, a physiological recording electrode that can beused without skin preparation or with or without the use of electrolyticgels. The invention is further directed to the shape of thephysiological device of the electrode's lower surface, variousconnection geometries, as well as a variety of configurations of surfacestructures on the physiological recording electrode's lower surface.These surface structures have various lengths, widths, and heights,which are preferably durable, rigid and resist breaking, and arecapable, at least in part, of transmitting an electric potential fromthe epidermis of the skin which can be measured. The surface structuresmay be used to limit the depth of application, to anchor the device orpreferably electrode during normal application, to penetrate the skinsurface, to displace or move hair and detritus, and/or allow for uniformapplication of the electrode or other device over unprepared skin.

The physiological recording device or electrode, having an upper and alower surface, can take many forms. For instance, the lower surface canbe flat, concave, convex, or some other unique shape. Variousembodiments of the present invention could include changes in thephysiological recording device's lower surface. The physiologicalrecording device can be substantially flat on its lower surface. Whetherthe lower surface is perpendicular to the device's vertical axis, orcontoured depends on the application. The physiological recording devicecan also be substantially concave on its lower surface. An example iswhere the lower surface is outwardly curved like the inner surface of asphere. The physiological recording device can also have a convex shapeon its lower surface. An example is where the lower surface curves orbulges outward, like the exterior of a sphere. The lower surface of thephysiological recording device is not limited to one of theaforementioned shapes, and may take on a number of other unique shapesor some combination of the shapes listed above.

The physiological recording device of the present invention may includea number of surface features, preferably elevated surface features.These elevated surface features may take one of many forms including,but not limited to, ridges, columns, penetrators, anchors, epidermalstops and combinations thereof. These surface features, in general,protrude from the various shaped substrates described above. Preferably,there is at least one structure or surface feature protruding from theelectrode's lower surface.

The ridge(s) of the present invention is a long, narrow structure orelevation. Preferably, the size and shape of the ridge is such that theridge(s) will not break during normal use, and/or will anchor theelectrode to prevent motion artifacts or any substantial movement of theelectrode with respect to the skin. Therefore, preferably, theappropriate aspect ratio of the height to the length of the ridge isselected to make an electrode wherein the ridge(s) will not break, andwill better anchor the electrode during application. The height of theridge(s) is measured from the edge of the ridge perpendicular to thesubstrate. The ridge(s), preferably, has a height from about 20 to about1000 μm, more preferably from about 40 to about 1000 μm, even morepreferably from about 100 to about 500 um, and most preferably fromabout 100 to about 350 um. The aspect ratio, for purposes of thisinvention, of the ridge is a ratio of the average height of the ridgedivided by the average width of the base of the ridge. The average widthof the ridge is measured by taking the width of the based of the ridgealong the length and comparing it to the average height of the ridgealong the length of the ridge. The ridge(s), preferably, has an aspectratio of less than about 8:1; more preferably less than about 6:1; evenmore preferably less than about 4:1; still more preferably less thanabout 2:1; even still more preferably less than about 1.5:1; and mostpreferably less than about 1:1. The ridge(s), preferably, has a lengthto height aspect ratio. The length to height aspect ratio is the lengthof the ridge or its longest dimension divided by the average height ofthe ridge. Preferably, the length to height aspect ratio of the ridge(s)is greater than about 2:1, more preferably greater than about 4:1, evenmore preferably of greater than about 8:1 and most preferably of greaterthan about 15:1.

The ridge(s) further can have a variety of cross sections over thelength. Examples of these cross sections include, but are not limitedto, a square, rectangle or trapezoid, a pointed surface like that of atriangle, a domed surface like that of an arch or arc, a cross sectionwith a concave surface between to ridge lines forming the two ridgelines, some other unique cross-section or the like. The cross section ofthe ridge extends for a length. The surface of the ridge away from thesubstrate, when applied to the skin surface, depresses, and does notreadily pierce, the skin such that it anchors the electrode in place,increases the surface area of the electrode in contact with the skin,displaces or moves hair and detritus and is capable, in part, oftransmitting an electric potential which can be measured from the skinthrough the ridge.

A column(s) is another type or form of structure or elevation that canbe used in various embodiments of the present invention. Preferably, thesize and shape of the column is such that the column(s) will not breakduring normal use, and/or will anchor the electrode to prevent motionartifacts or any substantial movement. Therefore, preferably, theappropriate aspect ratio of a column is selected to make an electrodewherein the column(s) will not break, and will better anchor theelectrode during application. The height of the column(s) is measuredfrom the edge of the ridge perpendicular to the substrate. Thecolumn(s), preferably, has a height from about 20 to about 1000 μm, morepreferably from about 40 to about 800 μM, even more preferably fromabout 100 to about 500 um, and most preferably from about 150 to about350 um. The aspect ratio of the column is a ratio of the average heightdivided by the average width of the base of the column. The column(s),preferably, has an aspect ratio of less than about 4:1, more preferablyless than about 2:1, even more preferably less than about 1.5:1, andmost preferably less than about 1:1. The column(s) can have a variety ofcross sections over its height and width. Examples of these crosssections include but are not limited to a square, circle, rectangle ortrapezoid, a pointed surface like that of a triangle, a domed surfacelike that of an arch or arc, a cross section with a concave surfacebetween two points (wherein the distance from the base to either pointis greatest height of the column for the cross-section), some otherunique cross-section or the like, provided that the shape doesn't piercethe skin under normal conditions. The cross section of the column like aridge extends for a length. However, the length of the column ispreferably in proportion to the height of the cross-section of thecolumn, and more preferably shorter than the height of the column. Thesurface of the column away from the substrate, when applied to the skinsurface, depresses, and does not readily pierce, the skin such that itanchors the electrode in place, displaces or moves hair and detritus,increases the surface area of the electrode in contact with the skin,and is capable, in part, of transmitting an electric potential from theskin through the ridge which can be measured.

Penetrator(s), as used in various embodiments of the present invention,are sized and shaped for piercing or depressing the stratum corneum orouter layer of the epidermis, displacing or moving hair and detritus andaccessing the lower layers of the epidermis. The penetrator can takemany shapes including but not limited to pyramidal, needle-like,triangular, or any other shape that can be tapered to a point or tip.The surface of the penetrator away from the substrate, when applied tothe skin surface, readily pierces or depresses the skin, preferablyanchors the electrode in place to prevent motion artifacts or anysubstantial movement, displaces or moves hair and detritus increases thesurface area of the electrode in contact with the skin and lower layersof the epidermis, and is capable, in part, of transmitting an electricpotential which can be measured from the skin and lower layers of theepidermis through the penetrator.

Preferably, the penetrator(s) and other surface features are configuredso as to minimize the chance of the penetrator(s) entering the dermisarea of the skin thereby causing discomfort. Preferably, the size andshape of the penetrator is such that the penetrator(s) will not breakduring normal use, will limit the depth the penetrator enters the skinunder typical application conditions, and/or will anchor the electrodeto prevent motion artifacts or any substantial movement. Therefore,preferably, the appropriate aspect ratio of the height to the averagewidth of the penetrator, contour of the edge(s) or side(s) of thepenetrator, and/or height of the penetrator are selected to make anelectrode wherein the penetrator(s) will not break, and will betteranchor the electrode during application. The height of the penetrator(s)is measured from the tip of the penetrator perpendicular to thesubstrate. The penetrator(s), preferably, has a height from about 20 toabout 750 μm, more preferably from about 40 to about 500 μm, even morepreferably from about 50 to about 250 μm, and most preferably from about50 to about 150 μm. The aspect ratio of the penetrator is ratio of theheight divided by the average width of the penetrator. The average widthof the penetrator is measured by taking the average width of thecross-sections of the penetrator at its base perpendicular to theheight. The penetrator(s), preferably, has an aspect ratio of less thanabout 5, more preferably of less than about 2, even more preferably ofless than about 1.5 and most preferably of less than about 0.75. Theslope of the edge(s) or side(s) of the penetrator is measured by drawinga line tangent to the edge or the side of the penetrator(s) at any givenpoint to the substrate and measuring the angle between the line andwhere it intersects the upper surface of the substrate. While it isunderstood that the slope may or may not vary substantially along theedge or side of the penetrator(s), preferably the slope is less thanabout 80 degrees over substantially all of the edge or side of thepenetrator, more preferably is less than about 70 degrees, and mostpreferably is less than about 60 degrees. By substantially all of theedge or side of the penetrator, it is meant that 60% of the length ofthe edge or side has a slope less than that set forth above. However,preferably, 75% of the length of the edge or side has a slope of lessthan that set forth and more preferably 90% of the length of the edge orside has a slope of less than that set forth.

The epidermis or epidermal stop(s) of the present invention is astructure or elevation. Epidermis or epidermal stops are structures of aparticular height with respect to the height of the penetrator(s) orother surface features so as to prevent the penetrator(s) or othersurface features from unduly penetrating into the dermis of the skin ordistorting the surface of the skin, respectively, where they might causediscomfort to the subject. An epidermis or epidermal stop(s) may also beincorporated into a penetrator, ridge, column, or like surface featureor can be a separate surface feature. Further preferably, the distancebetween the adjacent epidermal stops and penetrator(s) or surfacefeatures or adjacent penetrators or surface features is at least 80 μmat their nearest points, more preferably at least 160 μm and mostpreferably at least 250 μm. The epidermal stops may, however, have anyshape known to those skilled in the art that would effectively preventthe penetrator(s) from entering the dermis of the skin. Furthermore, theepidermal stops are preferably applied in an array between thepenetrators, therefore further minimizing inadvertent deep penetrationor over penetration by the penetrator(s) or minimizing significantdistortion of the skin by other surface structures. If the epidermalstop is a separate surface feature, preferably, the epidermal stop incombination with at least one other surface feature creates a detritustrough.

A detritus trough is the area interposed between adjacent surfacestructures or features. These troughs allow for a more accurateplacement of the surface features by allowing for displacement ormovement of the hair and other detritus on the skin in these troughs.Preferably, the detritus troughs are sufficient in number and size toallow for placement of the device on skin with a significant amount ofhair such as for example the scalp or the chest of a male subject.Detritus troughs are created to maximize the area available for optimaldevice to skin contact, by improving the probability that hair and otherdetritus will enter the troughs and not preventing the surface featuresfrom either coming in contact with the skin or penetrating the skin.

The anchor(s) of the present invention is a structure or elevation thatstabilizes the physiological device against a subject's skin. Thisstabilization further preferably prevents, or reduces, motion artifactsin the electrophysiological signal from the device, or any substantialmovement. Motion artifacts that are generated in biopotential electrodesare induced by disrupting the electrical paths due to slipping, as wellas by disturbance of the electrical double layer at the interfaces. Theanchors reduce the chances for movement, and/or separation from thesubject's skin. While the anchor can also be any of the structuresdescribed above, the anchor also can serve no other purpose except tostabilize or reduce movement of the device on the subject's skin. Theanchor(s) can have a variety of cross sections over a length, alldescribed above.

It is understood that the physiological recording devices of the presentinvention may have a combination of the various surface featuresdescribed above. Various specific embodiments for the present inventionare described as follows: In one embodiment, the present inventionincludes a physiological recording device comprising a substrate havingan upper and a lower surface, and at least one ridge(s) formed on thelower surface, having a length, width, and height, wherein the ridge(s)depresses or pierces the stratum corneum or outer layer of the skin, andis capable of transmitting an electric potential that can be measuredfrom the skin through the ridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, at least one ridge(s) formed on the lower surface, and at leastone penetrator wherein the penetrator is capable of depressing orpiercing through the stratum corneum or outer layer of the skin, theridge(s) pierces or depresses the stratum corneum or outer layer of theskin, and both the penetrator and ridge in combination are capable, atleast in part, of transmitting an electric potential that can bemeasured from the skin.

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms an arc whereinthe ridge(s) depresses and/or pierces the stratum corneum or outer layerof the skin and is capable, at least in part, of transmitting anelectric potential that can be measured from the skin through theridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms a trapezoidwherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and is capable, at least in part, oftransmitting an electric potential that can be measured from the skinthrough the ridge(s).

In another embodiment, the present invention includes a physiologicalrecording device comprising a substrate having an upper and a lowersurface, and at least one ridge formed on the lower surface, the crosssection of the at least one ridge at least in part forms a trianglewherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and capable, at least in part, of transmittingan electric potential that can be measured from the skin through theridge(s).

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, and at least one ridge formed on the lower surface,the cross section of the at least one ridge at least in part formscup-like, parabolic end comprising two outer points and an inner bowlwherein the ridge(s) depresses and/or pierces the stratum corneum orouter layer of the skin, and capable, at least in part, of transmittingan electric potential that can be measured from the skin through theridge(s).

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially convex and at least one structure being formed on thelower surface, wherein the structure is capable, at least in part, oftransmitting an electric potential that can be measured from the skin.

In even still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially concave and at least one structure being formed on thelower surface, wherein the structure is capable, at least in part, oftransmitting an electric potential that can be measured from the skin.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate beingsubstantially curved and at least two structures being formed on thelower surface, the at least two structures both having different heightsand/or shapes, wherein the at least two structures are capable, at leastin part, of transmitting an electric potential that can be measured fromthe skin.

In still another embodiment, the present invention includes aphysiological recording device comprising a substrate having an upperand a lower surface, the lower surface of the substrate not beingsubstantially convex, concave, or flat, but rather is neither uniformnor substantially symmetric, and at least two structures being formed onthe lower surface, the at least two structures both having differentheights and/or shapes, wherein the at least two structures are capable,at least in part, of transmitting an electric potential that can bemeasured from the skin.

In still another embodiment, the present invention includes aphysiological recording device for measuring physiological signals fromthe skin of subject comprising a substrate having an upper and a lowersurface, and at least one structure being formed on the lower surface,wherein the at least one structure does not readily pierce the skin ofthe subject, assists in anchoring the physiological recording device tothe skin of the subject and is capable, at least in part, oftransmitting an electric potential from the skin that can be measured.

The penetrating recording device, and in particular one specificembodiment, the physiological electrode of the present invention, can beformed from a variety of processes and materials known to those skilledin the art. The substrate from which the penetrators or other surfacefeatures are formed or to which they are added can by way of example butnot limitation be made from the following: conductive metal sheet andconductive metals including for example stainless steel, nickel andcopper; semi-conductive metal including for example silicon and dopedsilicon wafers; ceramics including for example oxides; and polymersincluding for example electrically insulating polymers such aspolyimides. Preferably, all non-conductive substrates are coated ordoped to make the substrate semi-conductive or conductive. There are ingeneral four processes by which embodiments of the present invention arepreferably manufactured.

The first, and most preferable, process is where the electrode is formedby injection molding, casting or depositing a material into a mold toproduce a dry electrode that is comprised of single piece construction,or optionally multiple piece construction. Another process that may beused is where the lower surface of the electrode is formed byreplication techniques such as using a replication roll, which forms thenegative image of the desired surface features of the lower surface ofthe electrode or by stamping or pressing different materials. Inreplication, a web of polymer material in the form of sheet or film isheated to soften the material and then passed over or under areplication roll to form the desired surface features of the lowersurface of the device or electrode, generally, hundreds to thousands topossibly even millions of times over the length of the web of polymermaterial. The replicating roll is either internally cooled causing theweb to re-harden during replication, or the web of polymer material iscooled to re-harden the polymer material after replication but prior tore-winding the web. In replication, the replicator could also be heatedto allow for modifying the polymer material. The replicator processedweb of polymer material can then be diced or sliced at some point intoindividual pieces, which form the lower surface of the physiologicalrecording device or electrode. Similarly, the lower surface of devicesor electrodes can be stamped or pressed from polymer sheet or polymerpowders respectively. In the case of stamped devices or electrodes, apolymer sheet material is drawn to create the surface features. In thecase of pressed devices or electrodes, polymer powders are pressed thensintered.

Preferably, the mold, replication or embossing method of the presentinvention also includes a method to roughen the surface of the electrodeor device surface. Roughening of the surface of the mold or areplicating roll can be accomplished for example by shot peening thesurface. Shot peening is the use of hardened balls or materials whichare impacted against the surface to not only create roughening but tostrengthen the surface. More preferably, a #30 glass impact bead is usedto shot peen the surface of the mold. By roughening the surface of themold, the electrodes or devices formed in the mold have a likewiseroughened surface. This not only improves the adhesion of an adhesivecollar used about the neck of the electrode or device, but also createsan electrode or device that will better anchor to the subject. Theelectrode or device could also be roughed by abrading or roughening themolded or replicated surface.

Preferably, the device or electrode is formed using an injection moldingtechnique. The injection mold is preferably formed from a metal, morepreferably, the mold has porous mold inserts in the areas requiring finedetail, and most preferably the sintered or other types of porous moldinserts are made out of materials such as Porcerax II. These sinteredporous materials have a system of interconnected pores dispersedthroughout the material. These types of materials, when used inappropriate areas, eliminates gas buildup, reduces injection pressure,lowers cycle times, gloss levels and substantially reduces scrap andreject rates. This type of sintered mold insert also allows for theproduction of the very fine micro-features or surface structures thatpopulate the device or electrode's lower surface by allowing for theremoval of air from the mold when creating these features. Porcerax IIis a sintered porous metal with porosity in the range of 20 to 30% byvolume, and requires complex machining, polishing, cleaning, andmaintenance. These inserts help to eliminate trapped gases allowing forbetter venting within the mold. By proper design of the mold with theproper inserts and vent lines the devices or electrodes can be madewithout burning, shrinkage, short shots and improved appearance. Theseinserts also allow for a dull matte finish leading to better performanceof the devices or electrodes in their application to the subject's skin.Preferably, the inserts have a pore size from about 5 to about 30microns, a porosity of from about 15 to about 35% by volume, and alinear expansion which makes it compatible with the rest of the moldover the temperature range of the materials being molded. In formingwhile grinding and/or milling may be used, a method know as stoningwhich uses a back and forth or side to side method is used to removemetal that is crushed over the pores and to re-establish permeability oreven more preferably a method known as electric discharge machining isused to re-establish permeability. Preferably, also the porous insert isconnected to an exhaust line which facilitates the removal of gases fromthe mold cavity through the inserts during the molding process.

The mold is designed such that the imprint, or negative image, of thedesired surface features that may include the penetrators, anchors,ridges, columns, detritus troughs, epidermal stops, and combinationsthereof are formed to allow the substantial escape of gas during themolding process in the areas where these micro-features are formed. Theinjection mold may also require a core pin to mold the undercut of thesnap stud in once piece, if a snap stud is the method of connection. Thesnap stud feature is created to maintain compatibility with mostexisting electrode snap connectors. As described later, however, thereare other embodiments that are contemplated which allow for other typesof connection of the devices or electrodes of the present invention withconnecting wires or leads. The mold may be filled via injection molding,casting, deposition or other material forming technique to produce thedesired device or electrode. Preferably, the material that actuallyforms the device or electrode is a polymer, more preferably the materialis a thermoplastic, still more preferably the material is a liquidcrystal polymer resin, and even more preferably the material is ABS. ABSis a material that offers unique combinations of toughness, stiffness,low mold shrinkage, and excellent flow properties which are allessential for the production of micro-features.

Once formed, the devices or electrodes are ejected and cooled. Thedevice or electrode is then trimmed to remove any imperfections or toimpart any device or electrode characteristics, which cannot be obtainedthrough molding. Optionally, and as a function of the conductivity ofthe material utilized, the surface may be further doped to increase theconductivity of the device or electrode surface or of just the surfacefeatures, and also various film layers and leads can be coated onto thedevice or electrode to make it individually addressable or to functionas desired in an array of electrodes. Preferably, the electrode iscoated with a conductive metal surface via physical vapor deposition(PVD), or sputtering. The deposition material, silver or gold, istransferred to the substrate material with such energy as to cause themetal to intermingle with the substrate at the atomic level. Morepreferably, however, the electrode is coated with an electroplatingtechnique using silver or gold coatings. Even more preferably, theelectrode is coated with silver-silver chloride (Ag/Ag—Cl) which resultsin a non-polarizable electrode with better ohmic behavior and greaterelectrical stability (less noise). In coating the electrode withsilver-silver chloride a standard electroplating process is used. Theelectrodes after coating, however, are not polished, which maintains aroughened surface thereby improving skin surface contact, and if anadhesive collar is used adhesion of the collar to the surface of theelectrode.

A second general method of processing the device or electrode is byforming the device or electrode from silicon wafers. In the first stepof this process, an oxide layer is formed on the silicon wafer.Following growth of the oxide layer, a photo resist (not shown) isapplied and the pattern for the major surface features is transferredusing a conventional photo resist process. Following application of thephoto resist, the wafers etched to form the surface features. Ifepidermis stops are not desired then further etching of the wafer takesplace to form the desired surface features. If, however, epidermis stopsare desired, following the anisotropic etch, the surface of the siliconwafer is stripped of all oxides and masking material. Again, anotheroxide layer is formed on the silicon wafer. Following the growth of theoxide layer, a fairly thick photo resist is applied to the upper surfaceof the silicon wafer. Again, the photo resist is masked with a patternbut this time for the epidermis stops. Then a second bulk anisotropicetch is used to form the epidermis stops and to finish the surfacefeatures. After etching is completed, the remaining oxide is removed. Atthis point, the silicon optionally can be doped to increase theconductivity of the electrode, and also various film layers and leadscan be coated onto the electrode to make surface features individuallyaddressable or to function as desired in an array of electrodes.

A third general process for forming the device or electrode is by anadditive deposition process. Preferably, an electroplating process isused. Preferably, the substrate for this process is a flexible polymer,and more preferably an insulating polymer such as a polyimide. With thisprocess a thin layer of metal is applied to the substrate. Then, a thicklayer of photo resist is applied to the thin layer of metal on thesubstrate and patterned by photolithography to create the desiredsurface features. These patterns form the base of the device orelectrodes and the various surface features of the device or electrode.The photo resist is stripped from the substrate. Another layer ofphotoresist is applied. These patterns further define the surfacestructure which is built up to the desired height and shape byelectroplating. Optionally, at this point various film layers and leadscan be coated onto the electrode to make the surface featuresindividually addressable or to function to improve the conductivity asdesired in an array of electrodes.

Finally, a fourth process, for forming the device or electrode is from ametal sheet through photo micro-machining techniques. These techniquescan be used to form the penetrator(s), ridges, anchors, columns,(epidermal stops, detritus troughs and springs, if desired), andcombinations thereof. With this process one edge of a thin gauge stockof metal, preferably stainless steel, is photo defined and chemicallyetched, effectively forming a thin cross section of a desired twodimensional surface containing at least one of the above surfacefeatures described above. At this point various film layers, specificcoatings and leads can be coated or deposited onto the electrode to makeit individually addressable or to function as desired in an array. Thisforms a device or electrode with a cross section with approximately thethickness of the thin gauge metal stock. Stainless steel is preferredbecause of its good biocompatibility, excellent corrosion resistance,and because of its ability to be cleaned and reused, however, a varietyof other materials known in the art can also be used. A device orelectrode array can be formed by stacking or laminating many of thesethin strip electrodes together. Additionally, laser machining, abrasionand other metal working techniques may be used to produce the electrode.

Preferably, the devices or electrodes of the present invention are of amonolithic design. That is the electrical connector of the device orelectrode is incorporated by molding or other manufacturing process intothe same substrate in which the surface features are part of. Thismonolithic or one piece design creates an electrode or device withbetter signal

The devices or electrodes of the present invention can be used in avariety of applications including for measuring various biopotentialsincluding but not limited to ECG, EEG, EMG, and EOG, and for takingother physiological measurements that can be determined from the skin orsubcutaneous layers of the subject. The physiological recordingelectrode or device can be packaged by conventional packagingtechniques, however, preferably the package provides 1) adequatestructural support for the electrode so it can be handled roughly (i.e.,dropped, crushed, etc) without damage; 2) a means (e.g., tape, belt orspring) preferably, to force the electrode or device against thesubjects skin with a consistent pressure; 3) a low impedance path fromthe electrode's or device's surface to the package's output connector;and 4) a design which allows for easy cleaning and sterilization forapplications requiring reuse. These electrode or device packages alsocan be mounted to the skin using conventional techniques such asadhesives, harnesses or bands.

The devices or physiological recording electrodes are applied to asubject, which can be an animal or human body having skin comprising anepidermis comprising a stratum corneum layer and lower layers of theepidermis, and a dermis. The ridge(s), column(s), and/or penetrator(s),in particular, of the device or electrode can anchor the device to orpierce through the stratum corneum layer of the skin with thepenetrator(s) such that the penetrator(s) does not enter the dermis ofthe skin. The surface structures increase the surface contact with theskin and transforms a portion of the ionic current into an electricvoltage that can be transmitted through these individual surfacefeatures.

The devices or electrodes of the present invention can have varioustypes of connectors formed on the top or upper surface of the device orelectrode. The connector can simply be a common button type connectionin order to connect to standard terminals for various devices or can beshaped to provide for unique connecting features in order to requirespecial terminals to be created for the monitoring device.

The ridges, columns and penetrators also increase the amount of surfacearea of the skin in contact with the device or electrode, which isapplied. Preferably, the combination and the detail of the elevatedsurface structures increases the surface area of the lower surface ofthe device or electrode by at least 25%, more preferably by at least50%, even more preferably by at least 75%, even more preferably by atleast 150%, still more preferably by at least 250% and most preferablyby at least 400%. This allows for greater pick up of (or stronger)signals from the skin's surface, and further allows for the device orelectrode to be better anchored to the subject's skin resulting in lessartifacts to the signal through movement and the like. The electricvoltage from these surface features is measured using conventionalmeasuring devices.

The Applicants herein incorporate by reference the disclosures of U.S.patent application Ser. Nos. 11/454,520, 10/988,358 and 11/401,559.

FIG. 2 is a cross-sectional view of the epidermis layer and anillustration of the insertion of the penetrator(s) of the presentinvention into the epidermis layer. The physiological recordingelectrode 10 is comprised of a substrate 12 having an upper surface 14and a lower surface 13. The lower surface 13 of the substrate 12comprising at least one penetrator(s) 16 sized and shaped for piercingthe stratum corneum or outer layer of the epidermis, and accessing thelower layers of the epidermis. The penetrator 16 can take many shapesincluding but not limited to pyramidal, needle-like, triangular, or anyother shape that can be tapered to a point or tip. Preferably, the sizeand shape of the penetrator 16 is such that the penetrator(s) 16 willnot break or bend during normal use, will limit the depth the penetratorenters the skin under typical application conditions, and/or will anchorthe electrode 10 to prevent motion artifacts or any substantialmovement. Therefore, preferably, the appropriate aspect ratio of theheight to the average width of the penetrator 16, slope of the edge(s)or side(s) of the penetrator 16, and/or height of the penetrator 16 areselected to make an electrode 10 wherein the penetrator(s) 16 will notbreak or bend, and will better anchor the electrode 10 duringapplication. The height of the penetrator(s) is measured from the tip ofthe penetrator 16 perpendicular to the substrate 12.

FIGS. 3-24 show various specific embodiments of the present invention,including mainly different examples of the variations in the surfacefeatures, the variations of the surface shapes and combinations thereof.

Referring now to the attached figures, FIG. 3 is an isometric view ofthe upper surface of a device or an electrode 10. The device orelectrode 10 is comprised of a substrate 12 having a upper 14 and lower13 surfaces (the edge of which is shown). The lower surface 13 of thedevice or electrode has a connector 18 and a base 20 for the connectorwhich provides structural support for both the connector 18 and theelectrode's 10 structural or upper surface 14. The connector 18 in thisparticular embodiment is a button type of connector, which connects tostandard leads used with electrodes or similar devices. The connector14, however, can be snap type of electrode formed from a variety ofshapes as mentioned earlier, can be a surface to which a lead can bemechanically attached by other devices, can be a surface to which a leadcan be bonded or can be a surface to which any of a number of standardtypes of leads can be attached.

FIG. 4 is an isometric view highlighting the lower surface 13 of oneembodiment of an electrode 10. The electrode 10 in FIG. 4 is shown withfour rows of penetrators 16 that are pyramidal in shape on a flat lowersurface 13 of the electrode 10. The flat lower surface 13 is preferablyused when attaching the electrode to a location on a subject that is notrounded or bony, for example like the chest, back, stomach, or portionsof the extremities of a subject.

FIG. 5 is a side view of an electrode 10 with a convex lower surface 13.The electrode comprises a substrate 12 with an lower 13 and upper 14surfaces. A base for the connector 20 is on the upper surface 14. Astandard snap type connector 18 is attached to the base 20. Theelectrode 10 is populated with penetrators 16 on the lower surface 13which are needle-like in shape, and generally are approximately the sameheight. The convex nature of the electrode's lower surface 22 may aid inapplication of the electrode 10 to an area on a subject that isdepressed such as areas near the sternum, armpit and the like.Preferably, penetrators 16 on such a device or electrode 10 are of suchheight that the points of their tips if connected would form a curvethat is generally parallel to the curvature of the lower surface 13.

FIG. 6 is a side view of another embodiment of a physiological recordingelectrode 10. The electrode 10 comprises a substrate 12 with an lower 13and upper 14 surfaces. A base for the connector 20 is on the uppersurface 14. A standard snap type connector 18 is attached to the base20. The electrode 10 has a convex lower surface 13 populated withpenetrators 16 that are needle-like in shape, and varying in height inproportion to the curvature of the surface so that their tips all arepoints that if connected would approximate a straight line. Thisembodiment of the present invention may aid in application to a flatarea on the subject's body such as the chest, back, or stomach.

FIG. 7 is a side view of another embodiment of a physiological recordingelectrode 10. The electrode 10 comprises a substrate 12 with an upper 14and lower surface 13. A base for the connector 20 is on the uppersurface 14. A standard snap type connector 18 is attached to the base20. The electrode 10 has a concave lower surface 13 populated withpenetrators 16 that are approximately the same height, so that theirtips all are points that if connected would form a curve that issubstantially parallel to the curvature of the lower surface 13. Thisalso may aid in the application of the electrode to a curved or bonyarea on the subject's body such as a wrist, a finger, ankle, or knee.

FIG. 8. is a side view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower surface 13. A base for the connector 20 is on theupper surface 14. A standard snap type connector 18 is attached to thebase 20. The electrode 10 has a concave lower surface 13 populated withpenetrators 16 that are pyramidal in shape and are varying in height inproportion to the curvature of the upper surface 13 so that their tipsall are points that if connected would form or approximate a straightline. This embodiment of the present invention may also aid inapplication to a flat area on the subject's body such as their chest,back, or stomach.

FIG. 9. is a side view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower surface 13. A base for the connector 20 is on theupper surface 14. A standard snap type connector 18 is attached to thebase 20. The electrode 10 has a convex lower surface 13 populated withpenetrators 16 that are needle-like in shape, ridges 24 with a heightslightly lower than the penetrators 16, and epidermal stops 22 that aresignificantly shorter than the height than the penetrators 16. Thepenetrators 16 readily pierce the skin, but are limited as to how deepthey can penetrate into the skin by both the epidermis stops 22 and theridges 24. The ridges 70 further depress the subject's skin allowing forgreater surface contact and acting further to limit the depth ofpenetration of the penetrators 16. The ridges 24 have a trapezoidalcross section and extend over length (not shown).

FIG. 10 is a side view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower surface 13. A base for the connector 20 is on theupper surface 14. A standard snap type connector 18 is attached to thebase 20. The electrode 10 has a convex lower surface 22 populated withcolumns 26 that are approximately the same height, and have a slightlytapered edge 28. The columns 26 depress the subject's skin increasingthe surface area of the upper surface 13 of the electrode 10 in contactwith the subject's skin, but may not pierce or penetrate the skin.

FIG. 11 is a side view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A standard snap type connector 18 is attached to thebase 20. The electrode 10 has a flat lower surface 13 populated withpenetrators 16 that are pyramidal in shape and vary in height to form adome-like shape of penetrator 16 tips.

FIG. 12 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has on its flat lower surface 13 with a spiralarrangement or pattern 28 of penetrators 16. The details of thepenetrators 16 are better viewed in the call out 30, which shows apyramidal shaped penetrators 16.

FIG. 13 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has on its flat lower surface 13 concentric rings or acircular arrangement or pattern 32 of ridges 24. The details of theridges 24 are better viewed in the call out 30, which shows a ridge 24with a trapezoidal cross section 34 over a length of a ridge 36. Theconcentric arrangement of rings enhance the electrode-skin interface,and improve subject comfort by creating space for hair, detritus, air,and/or moisture to flow or collect.

FIG. 14 a) is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has on its flat lower surface 13 five straight ridges24 extending over a length 36. The details of the ridges 24 are betterviewed in the call out 30, which shows a ridge 24 with a trapezoidalcross section 34 over a length of a ridge 36. The linear spacing of theridges 24 also enhances the electrode-skin interface, and improvessubject comfort by creating space or detritus trough 38 for hair,detritus, air, and/or moisture to flow or collect.

FIG. 14 b) is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has on its flat lower surface 13 twelve groupings of afirst ridge 24 perpendicularly positioned with respect to a second ridge25. The details of the ridges 24, 25 are better viewed in the call out30, which shows a ridges 24, 25 with trapezoidal cross sections 34 overa length of a ridge 36. The linear and perpendicular spacing/placementof the ridges 24, 25 also enhances the electrode-skin interface, andimproves subject comfort by creating space or detritus trough 38 forhair, detritus, air, and/or moisture to flow or collect.

FIG. 15 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has on its flat lower surface 13 non-continuousconcentric rings or a circular arrangement or pattern 32 of ridges 24.The details of the ridges 24 are better viewed in the call out 30, whichshows a ridge 24 with a triangular cross section 40 over a length of aridge 36. The non-continuous concentric arrangement of rings enhancesthe electrode-skin interface, and improves subject comfort by creatingspace or a detritus trough 38 for hair, detritus, air, and/or moistureto flow or collect.

FIG. 16 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has four varying topographic regions or multiplesurface structures 42 on it's lower surface 13. The call out of themultiple surface structure regions 42 shows pyramidal penetrators 16 inone region, ridges 24 in another region, thatch-like or doublepenetrators 17 in another region, and a combination of ridges 24,penetrators 16 and epidermal stops 22 in another region in quadrants 44on the electrode's 10 flat upper surface 13. The arrangement of varyingsurface features enhance the electrode-skin interface, lowers theimpedance and improve the subject's comfort by creating space or adetritus trough 38 for hair, detritus, air, and/or moisture to flow orcollect.

FIG. 17 is a side view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A standard snap type connector 18 is attached to thebase 20. The electrode 10 has a flat lower surface 13 populated withthatch-like or double penetrators 17. The call out 30 shows in greaterdetail the features of the thatch-like or double penetrators 17.

FIG. 18 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has various raised surface features 46 on the lowersurface 13 in an almost L-shape. These raised surface features areinterlocking columns 26. The other raised surface features having aheight (not shown).

FIG. 19 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 has a large number of columns 26 on the lower surface13. These columns 26 are shown in more detail in the call out 30. In thecall out 30, the columns 26 have a concave or cup end 48 with twomicropenetrators 50. The arrangement of cup-ended columns enhances theelectrode-skin interface, and improves subject comfort by creating spaceor a detritus trough (not shown) for hair, detritus, air, and/ormoisture to flow or collect.

FIG. 20 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 with trapezoidal columns 26 on its flat lower surface13 arranged in clusters with channels 52. The arrangement of clusteredcolumns enhance the electrode-skin interface, and improve subjectcomfort by creating space or a detritus trough 38 for hair, detritus,air, and/or moisture to flow or collect.

FIG. 21 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 as shown in the cutout 30 with triangular ridges 24 onits flat lower surface 13 arranged in a seven small rings 54. Thearrangement of seven small rings 54 enhances the electrode-skininterface, and improves subject comfort by creating space or a detritustrough 38 for hair, detritus, air, and/or moisture to flow or collect.

FIG. 22 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 as shown in the callout 30 with triangular ridges 24 onits flat lower surface 13 arranged in non-concentric rings 56. Thearrangement of non-concentric rings 56 shown better in the callout 30enhances the electrode-skin interface, and improves subject comfort bycreating space or a detritus trough 38 for hair, detritus, air, and/ormoisture to flow or collect.

FIG. 23 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 is shown in the callout 30 with columns 26 withpyramidal caps 58 on its flat lower surface 13. The arrangement ofpyramidal columns shown better in the callout 30 enhances theelectrode-skin interface, and improves subject comfort by creating spaceor a detritus trough 38 for hair, detritus, air, and/or moisture to flowor collect. These columns 26 do not easily pierce the skin, like apyramidal penetrator, but rather merely depress the skin to anchor theelectrode.

FIG. 24 is an isometric view of another embodiment of a physiologicalrecording electrode 10. The electrode 10 comprises a substrate 12 withan upper 14 and lower 13 surfaces. A base for the connector 20 is on theupper surface 14. A connecting surface 18 is attached to the base 20.The electrode 10 as shown in the callout 30 with penetrators 16 that arepyramidal in shape on its flat upper surface 13 arranged in clusterswith channels 52 on the electrodes lower surface 13. The arrangement ofclustered penetrators enhances the electrode-skin interface, andimproves subject comfort by creating space or a detritus trough 38 forhair, detritus, air, and/or moisture to flow or collect.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of forming a physiological recording electrode having anupper surface and a lower surface, and desired surface features, theelectrode for measuring biopotentials from a subject having skin, themethod comprising the steps of: forming in a mold by injection molding,casting or deposition a physiological recording electrode comprising anupper surface and a lower surface, the upper surface comprising aconnector and the lower surface comprising at least one penetrator(s)protruding from the lower surface, wherein the at least one penetratorof the lower surface is capable of piercing through a stratum corneum orouter layer of the skin and transmitting an electric potential from alower layer of a epidermis of the skin of the subject.
 2. The method inclaim 1, further comprising the step of forming a mold comprising atleast one porous insert and at least one vent, the insert positioned inan area of a desired surface feature and comprising an openly porousmaterial, and the vent being positioned to allow for removal or escapeof gases formed in the method.
 3. The method in claim 2, furthercomprising the step of coating or depositing a conductive film layer onthe physiological recording electrode.
 4. The method in claim 1, furthercomprising the step of coating or depositing a conductive film layerover the surface of the at least one penetrator on the physiologicalrecording electrode after the physiological recording electrode has beenformed.
 5. The method in claim 1, wherein the physiological recordingelectrode is molded from a metal.
 6. The method in claim 1, furthercomprising the steps of forming a mold having a mold cavity androughening at least part of a surface of the mold cavity prior toforming the physiological recording electrode.
 7. The method in claim 1,further comprising the step of attaching an adhesive collar to thephysiological recording electrode, the adhesive collar being shaped toessentially surround the physiological recording electrode and hold theelectrode against the subject's skin.
 8. The method in claim 1, whereinthe connector is a male snap connector used for attaching to deviceswith leads for attaching to physiological electrodes.
 9. A method offorming a physiological recording electrode having an upper surface anda lower surface, and desired surface features, the electrode formeasuring biopotentials from a subject having skin, the methodcomprising the steps of: forming a physiological recording electrodefrom a polymer sheet or film from a replicating surface, the polymersheet or film having an image of the desired surface features of thephysiological recording electrode, the physiological recording electrodecomprising an upper surface and a lower surface, the lower surfacehaving at least one elevated surface structure or penetrator formed fromthe replicating surface, wherein the at least one elevated surfacestructure or penetrator is capable of transmitting an electric potentialfrom the skin of the subject.
 10. The method of claim 9, wherein thepolymer sheet or film further comprises a metallic or conductive surfacelayer, and the step of forming a physiological electrode from thepolymer sheet or film further comprises the steps of heating the polymersheet or film prior to forming by an embossing wheel and/or heating atthe same time as forming by the embossing wheel, and then cooling thepolymer sheet or film, at least partially.
 11. The method of claim 9,the step of forming a physiological electrode from the polymer sheet orfilm further comprises the steps of heating the polymer sheet or filmprior to forming by an embossing wheel and/or heating at the same timeas forming by the embossing wheel, and then cooling the polymer sheet orfilm, at least partially.
 12. The method in claim 11, further comprisingthe steps of coating or depositing a conductive film layer on thepolymer sheet or film and cutting the polymer sheet or film into pieceswith at least one elevated surface structure or penetrator per piecewherein the pieces can be used as at least a portion of a physiologicalrecording electrode or an array of physiological recording electrodes.13. The method in claim 11, further comprising the steps of cutting thepolymer sheet or film into pieces with at least one elevated surfacestructure or penetrator per piece and coating or depositing a conductivefilm layer on the pieces of polymer sheet or film wherein the pieces canbe used as at least a portion of a physiological recording electrode oran array of physiological recording electrodes.
 14. The method in claim12, further comprising the steps of attaching physiological recordingconnectors to pieces of the coated polymer sheet or film.
 15. A methodof forming a physiological recording electrode having an upper surfaceand a lower surface, and desired surface features, the electrode formeasuring biopotentials from a subject having skin, the methodcomprising the steps of: forming from thin gauge stock metal by photomicro-machining a physiological recording electrode comprising an uppersurface and a lower surface, the upper surface comprising a connectorand the lower surface comprising at least one penetrator(s) protrudingfrom the lower surface, wherein the at least one penetrator of the lowersurface is capable of piercing through a stratum corneum or outer layerof the skin and transmitting an electric potential from a lower layer ofa epidermis of the skin of the subject.
 16. The method of claim 15,further comprising the step of forming a thin cross section of a desiredtwo-dimensional surface containing at least one surface feature.
 17. Themethod of claim 16, further comprising the step of coating or depositinga conductive film layer on the physiological recording electrode afterthe physiological recording electrode has been formed.
 18. The method ofclaim 16, further comprising the step of stacking or laminating many ofthese thin strip electrodes together to form a device or electrodearray.
 19. The method of claim 15, further comprising the step ofattaching an adhesive collar to the physiological recording electrode,the adhesive collar being shaped to essentially surround thephysiological recording electrode and hold the electrode against thesubject's skin.
 20. The method of claim 15, wherein the connector is amale snap connector used for attaching to devices with leads forattaching to physiological electrodes.